It also will be an emotional night as the Democrats pay tribute to Sen. Ted Kennedy, who has brain cancer.

Beyond the personal and the emotional, the sales campaign moves to more substance Tuesday night with the focus on issue No. 1: the economy. The Democrats are calling their theme that night "Renewing America's Promise."

Sen. Hillary Clinton will be the headline prime-time speaker. This will be a critically important speech because so many of her supporters remain unconvinced about Obama. The tone she sets and the words she utters will send out a powerful message.

Former Virginia Gov. Mark Warner will deliver the keynote address that night. He is running for the U.S. Senate to succeed John Warner (no relation).

There's a history to these speeches. Obama delivered the keynote address at the Democrats' last convention, and we know where he wound up.